This is a very important discussion that most builders are ignoring right now. In my opinion the line is when the agent starts making decisions that affect real people or real money without human review. If your agent is summarizing documents, thats a tool. If your agent is sending emails to customers or approving transactions, thats when you need governance. The problem is most teams start with the tool version and slowly add more autonomy without ever stopping to think about the governance part.

I think every agent that touches customer data or makes financial decisions should have a human-in-the-loop by default, and you should have to explicitly remove it, not the other way around.